"The Feynman Lectures on Physics". Physics textbook by Richard P. Feynman, Robert B. Leighton, and Matthew Sands, volume I; lecture 44, "The Laws of Thermodynamics"; section 44-1, "Heat engines; the first law"; p. 44-2, 1964.
Erma Bombeck (2013). “The Erma Bombeck Collection: If Life Is a Bowl of Cherries, What Am I Doing in the Pits?, Motherhood, and The Grass Is Always Greener Over the Septic Tank”, p.119, Open Road Media